The 2012 Republican Convention (J. Scott Applewhite/AP) The 2012 Republican Convention (J. Scott Applewhite/Associated Press)

It’s a mystery how the chattering class arrives at any conclusion as to the “front-runner” in an election two years away with no declared candidates. First the “front-runner” was New Jersey Gov. Chris Christie; then, according to others, it was Sen. Rand Paul (R-Ky.), despite his obvious unacceptability to a significant segment of Republicans). The polls, if anything, reflect name identification, and in that department former governors Jeb Bush and Mike Huckabee generally lead — in a race neither may enter. That is what being a “front-runner” means on talking-head cable TV shows.

More relevant at this stage is figuring out who is likely to run. That’s a decision many candidates will make within the next six months. Each has his own calculus.

Christie’s slide in the polls seems to have abated. The bridge scandal hovers like low-hanging fog, not yet threatening a deluge but not dispersing. Christie could do well to stop generic discussions of whether principle or elections should be the driving force in politics; the discussion tends to rub even sympathetic listeners the wrong way. Instead, he would do better to begin formulating an agenda if he intends to run. His ideas and record will answer the question of whether he is “conservative enough.” He has personality to spare and remains one of the most talented and engaging personalities in the party, but without a vision of what he wants to do and specific examples, the discussion too often turns to political commentary. (Is he back? Is he distracted?) Unless the bottom falls out of his support, I suspect he’ll continue to position himself to run. The scandal and the ensuing semi-panic among donors, however, have encouraged others to think seriously about running; the field Christie could join may be more crowded than it would have been absent the bridge episode.

The real surprise this week comes from Sen. Marco Rubio (R-Fla.) who said he wouldn’t decide for another year (many other candidates will weigh in by the end of this year) and that he wouldn’t run for Senate and president simultaneously. He remarked: “I think by and large, when you choose to do something as big as that, you’ve really got to be focused on that and not have an exit strategy.”

This doesn’t entirely make sense. When would he call off a Senate run — before or after the first few primaries? Some candidates, of course, have not only kept their reelection prospects alive but remained on the ballot when they ran as the No. 2 on the presidential ticket (e.g. Vice President Biden, vice presidential nominee Paul Ryan). In his run for the White House in 1964, then-Sen. Barry Goldwater decided not to stand  for reelection to the Senate. (He ran again for Senate in 1968 and won.) Bob Dole resigned from the Senate in 1996 to run, but only having first secured the GOP presidential nomination.

Whether or not it is a political necessity, Rubio’s statement does two things. First, it puts some pressure on Paul, who has been trying to secure his right to be on the ballot in Kentucky both for offices to do the same. (Paul, who’s never seemed devoted to legislating anyway, might take him up on it.) Second, from our vantage point, it makes it less likely that Rubio will run. He’s a young man who’s shown devotion to public policy but who is in a dip in his career (post-immigration reform, post-shutdown). It would seem reckless to give up his seat and years of political viability for a problematic presidential run.

Following this line of reasoning, if Rubio decides not to run, his mentor, Jeb Bush, now the subject of considerable buzz, may have even more reason to run. His name recognition (and therefore his standing in meaningless polls) remains high; that means something to donors, supporters and the media, if nothing else. More important, the prospect of his run is being taken seriously — and it should be – because he is a mature, experienced candidate with a real agenda.

The main reason invoked against his run, the Bush name, is silly. Just as Hillary Clinton will insist on running on her own views, so would Bush. (At least with Jeb, the presidential father and brother won’t be reoccupying the White House.) He need not defend his brother’s positions with which he disagrees. Bush enjoys a pleasant, private (sort of) career and may not need to run, but the party may need him. If some other sound executive with center-right appeal and foreign policy credibility does not emerge from pack, the logic of his candidacy may become overwhelming. The notion of a “draft” is silly in an open primary process. Donors can back whomever they want, but it is primary voters who will assess the candidates and ultimately decide the race. No one — except maybe Hillary Clinton — gets anointed as his or her party’s presidential nominee.

Then there is Rep. Paul Ryan (R-Wis.). He seems to have thrown himself back into the legislative and policy arena, making no obvious efforts to set up a presidential organization or sweet-talk donors.  He’s a serious wonk, and the notion of taking the chairmanship of House Ways and Means only to hit the presidential campaign trail a few months later seems, well, unserious. The yen to shape the agenda and policy have always been there; a burning desire to be president has never been evident. Add into that equation the increasingly high visibility of Wisconsin Gov. Scott Walker (a Ryan friend and ally), and one suspects the latter is the more likely Wisconsin entry.

So if you follow the “Will he run?” meter rather than the polling froth, you’d have to say Christie is hanging in there and Rubio and Ryan are less likely to run; Bush and Walker are more likely. But it’s April 2014 and everyone has time to consider and reconsider their options. One thing to keep in mind is the rising importance of national security issues. That should and will encourage those with military experience (Texas Gov. Rick Perry), legislative experience in national security (Indiana Gov. Mike Pence), executive foreign policy experience (former U.N. ambassador John Bolton) or developed views on the importance of the United States’ role in the world (Bush). And the caveat that a year in politics is a lifetime should be liberally applied.

Jennifer Rubin writes the Right Turn blog for The Post, offering reported opinion from a conservative perspective.